Horizontal plane purge for precipitator



Nov. 3, 1959 R. F. RAWE 2,911,060

HORIZONTAL PLANE PURGE FOR PRECIPITATOR Filed Oct. 16, 1957 2092 f. Pane United States Patent HORIZONTAL PLANE PURGE FOR PRECIPITATOR Roger F.Rawe, Alfred, N.Y., assignor to APRA Precipitator Corporation, New York,N.Y., a corporation of Delaware Application October 16, 1957, Serial No.690,477 '5 Claims. (Cl. 183-7) This invention relates to gas cleaningapparatus of the electrostatic type and more specifically it relates toan arrangement for purging the collecting surfaces of an electrostaticprecipitator that are arranged in a rectangular housing.

In gas cleaning apparatus of the general type defined that utilizes acontinuous purging system, a large portion of the bulk of such apparatusis commonly allocated to house the mechanism and ductwork necessary forits satisfactory operation. Such apparatus is large and expensive tobuild and it frequently extends into the gas stream so as to providesubstantial opposition to the gas flowing therethr'ough- This inventiontherefore is 'directed to a simple arrangement for a purging apparatusthat is adapted to remove discrete material from collecting surfaces ofthe precipitatoron which it has been deposited by a process ofelectrostatic precipitation.

A primary object of this invention is to provide a purging system for anelectrostatic precipitator that is continuous in operation yet doesnot'interfere with normal operation of the precipitator.

Another object of this invention is to provide a purging system thatconstitutes a minimum of interference in the path of the main fluidflow.

A further object of' this invention is to provide a purging system foran electrostatic precipitator that is easily manufactured and simple tomaintain.

These and other objects of this invention willbecome more apparent whenread in conjunction with the accompanying drawings in which:

Figure l is a perspective view of a precipitator having a purging systemof the type herein defined.

Figure 2 is a side elevation of a precipitator having a modified form ofpurging arrangement.

Figure 1 of the drawings illustrates an electrostatic precipitatorhaving an inlet section 12 receiving dust bearing gases from a sourcenot illustrated. As the gas passes upward through the collectingcompartments 14 of the precipitator, particulate matter entrainedtherein is ionized and attracted to the collecting surface of theseveral compartments and the cleaned residual gas is exhausted upwardthrough outlet section 16 to an exhaust duct 18. Ionizing electrodes forthe compartments 14 are not illustrated since they form no part of thepresent invention.

As the dust deposits accumulate on the walls of the collectingcompartments the collecting efliciency of the apparatus is graduallylowered unless steps are inaugurated to systematically purge thecompartment walls of their deposits.

To this end apparatusfor this purging process enclosed in outlet section16 includes a series of ducts 22 with hoods 23 that are sized to cover acompartment 14 on which it is superposed to receive the dust bearing gasflowing thercthrough. The dust bearing gas flowing through the severalcompartments 14 flows at a normal therefrom and become electrostaticallyattracted to the.

compartment walls. When however the hood is superposed above aparticular compartment the velocity of the dust bearing gas passingtherethrough is increased to a high velocity whereby it re-entrains theparticles from the compartment walls and carries them through the hood23 and its connecting duct 22 to hopper 24. The opening 28 in wall 26through which duct 22 slidably passes is provided with sealing means topreclude leakage of fluid around duct 22 between outlet section 16 andhopper 24.

'The flow of high velocity fluid is brought about by an induced draftfan 36 having its suction 32 in hopper 24 to which the ducts 22 exhaust.The high velocity fluid which effects removal of the dust particles fromthe walls of the collecting compartments is drawn from the inlet ofhousing 10 through compartment 14, hood 23 and duct 22 to hopper 24,where due to lowered velocity, it releases a large portion of theparticulate matter removed from the walls of the chamber 14. Dustbearing gas drawn through induced draft fan 36 may be returned to theinlet of precipitator 10 for a repeat pass through the precipitator orit may be directed through other cleaning apparatus where it issubjected to further dust separation forces before it is exhausted tothe atmosphere.

Actuating means 38 mounted on hopper 24 is adapted to reciprocate theducts 22 and their integral hoppers 23 over the compartments 14 so as tosequentially subject each collecting unit to the flow of a high velocityfluid being induced by fan 36. The actuating means 38 illustratedincludes a motor 42 and worm gear reducer 44 that rotates a lead screwmechanism 46 that in turn moves the ducts 22 and attached hoods 23across the face of the compartments. Hydraulic or other mechanicalequivalents may readily be substituted for the actuat ing meansillustrated since the specific means is of no particular consequence tothis invention.

At each side of the precipitator housing a dead space 52 is formed toprovide a space on which the hoods 23 cated across the outlet section 16in response to actuationby the motor 38.

To compensate for the space requirements of purging ducts 22 and hoods23 in the outlet section 16, the size of the outlet section has beenincreased over that of the main precipitator 10. This increase in sizeprovides a substantially constant flow area for fluids flowing frominlet 12 to outlet 18.

Figure 2 illustrates a modified arrangement where ducts 22 and hoods 23are actuated from opposite sides ofrthe precipitator housing. Thisarrangement requires only one duct and interconnected hood assembly tobe positioned in the fluid stream at any one time to thereby provide aminimum of interference to the flowing fluid.

In practice each precipitator may be subdivided into a series ofjuxtaposed sections each of which is adapted to be progressively coveredby the purging mechanism as above described. Each motor 38 is actuatedin response to a predetermined sequence of operation by a time delayswitch or the like so that only one of the hood units will Patented Nov.3, 1959 be actively engaged in a purging capacity at any given time.While one hood is disposed in a purging attitude all other hoods areheld in a neutral position over a dead compartment 52 or 54 untilsuch-time as they will beactivated by the time delay switch.

While this purging mechanism has been described with reference to theseveral embodiments illustrated in. the drawing it is evident thatnumerous changes could be made without departing from the spirit of theinvention and it is intended that all matter contained in the abovedescription or shown in the accompanying drawings shall be, interpretedas illustrative and not in a limiting sense.

What I claim is:

l. Purging means for gas cleaning apparatus having a plurality ofparallel banks of collecting compartments enclosed in a housingcomprising; an outlet section superposed on said housing to provide acontinuous enclosure for the flow of gaseous fluid therethrough; a dusthopper at one side of said outlet section having a wall therebetweenincluding an opening adapted topermit communication between thecollecting compartments and said hopper; duct means extending throughsaid opening to direct fluid flow from a predetermined collectingcompartment to said hopper; and actuating means associated with; theduct means adapted to reciprocate said duct through the opening tosequentially subject the collecting compartments to a purging fluidflowing therethrough.

2. Purging means for gas cleaning apparatus including a plurality ofparallel banks of collecting elements enclosed in a housing comprising;an outlet section super posed on said housing to provide acontinuousenclosure for the flow of a gaseous fluid therethrough; a dusthopper at one side of said outlet section having a wall therebetweenincluding an opening adapted to permit communication between oppositesides thereof; duct means having a hood portion in communication with abank of collecting elements adapted to reciprocate through said opening;and actuating means associated with said duct: adapted to move the ductrelative to said parallelbanks of; collecting elements to sequentiallysubject said collecting elements to a purging fluid flowingtherethrough.

3. Purging meansfor gas cleaning apparatus having a plurality ofparallel banks of collecting elements enclosed in a housing comprisingan outlet section superposed on said housing to provide a continuousenclosure for the flow of gaseous fluid therethrough; a dust hopper atone side of said outlet section having a walltherebetween perforated toprovide an opening permitting communica: tion between the collectingelements and said hopper; duct means including a hood portion at one endadapted to cover a single bank of collecting elements to direct purgingfluid through said opening between the collecting elements and thehopper; a source of suction adapted to exhaust gaseous fluid from saidhopper to produce a high velocity purging fluid in the bank ofcollecting elements aligned with said hood; and means for reciprocatingsaid duct through the opening to sequentially subject adjacent banks ofcollecting elements to the purging fluid, being directed therethrough.

4. Purging means for gascleaning apparatus having a plurality ofparallel banks'of collecting elements enclosed in a housing comprising;an outlet section superposed on said housing providing a continuousenclosure for the flow of gaseous fluid therethrough; a dust hopperlaterally adjacent said outlet section having an apertured walltherebetween to provide a plurality of ports therethrough;

duct means extending through each port to provide communication betweenspaced collecting elements and the dust hopper; and means forreciprocating the ducts through the openings to progressively subjectthe collecting elements to the flow of purging fluid being inducedtherethrough.

5. Purging means for gas cleaning apparatus having a plurality ofparallel banks of collecting elements enclosed in a housing comprising;an outlet section superposed on said housing to provide a continuousenclosurefor the flow of gaseous fluid therethrough; hopper means-llaterally adjacent opposite sides of said outlet section each having acommon wall therewith containing at. least one opening permittingcommunication between the outlet section and each of the hoppers; andductmeans ex tending through said openings in opposite sides of theoutlet section to subject the collecting elements aligned with saidductsto the purgingeflect of fluid flow being induced therethrough.

References Cited in the fileof this patent UNITED STATES PATENTS1,957,560 Thomson May 8, 1934 2,731,107 Hersey Jan. 17, 1956 FOREIGNPATENTS 429,921 Germany June 8, 1926

